The authors of the book are a group of devoted early childhood specialists working in the Early Math Collaborative (EMC) at Erikson Institute. Erikson Institute is America's only graduate school focused exclusively on child development and early education from birth to age eight. The EMC aims to improve the quality of early math education and ensure that young children are introduced to foundational mathematics. The EMC provides professional development in early mathematics to nearly 100 preschool and kindergarten teachers each year. Our team works with teachers to bolster their math knowledge and confidence in their ability to teach it in fun, engaging, and developmentally appropriate ways. The ideas presented in this book are the result of a joined effort among the EMC team members over six years. They have been tested through our professional development programs. Together, the EMC team has accumulated over 150 years of classroom teaching and professional development experiences. The team also possesses a wealth of knowledge and expertise in areas such as child development, curriculum design, the development of mathematical thinking, classroom assessment, children's literature, instructional coaching, induction mentorship, bi-lingual education, and research design, to name a few. Below we present brief biographical sketches of the team members who contributed to this volume. Brownell, Jeanine O'Nan, (M.A.) Assistant Director of Programming for the EMC, Jeanine has extensive curriculum writing experience. She worked at the Center for Elementary Mathematics and Science Education at the University of Chicago. While there, she revised the first-grade component of the Everyday Mathematics curriculum and authored Pre-Kindergarten Everyday Mathematics. Jeanine has many years of experience as a classroom teacher of first, second, and third grades. She also has mentored new teachers and worked as an instructional coach. Chen, Jie-Qi (Ph.D.) Principal Investigator of the EMC, Jie-Qi is Professor of Child Development at Erikson Institute. She has taught preschool, elementary, and middle schools in China and preschool and kindergarten in the United States. She has contributed to teacher professional development efforts for more than 20 years and received the Outstanding Teacher Educator's Award in 2009 from the National Association of Early Childhood Teacher Educators. Jie-Qi has published six books and numerous articles. Her work focuses on teacher professi